KEAM 2014 Math Paper

Given equation of plane is
2x−y+2z−1=0....(i)
∴ DR's of normal to the given plane is (2,−1,2)
Given plane meet the z-axis.
Put x=0,y=0 in Eq. (i), we get
2(0)−0+2z−1=0
⇒‌‌z=

1

2

So, the point on z-axis is (0,0,‌

1

2

).
∴ Angle between normal to the plane and z -axis,
=‌

1

√4+1+4×‌ 1 2